Shortenings are generally produced by appropriate thermal and mechanical treatment of a mixture of several components. In the production of a conventional plastic shortening, lightly hydrogenated vegetable oils and intermediate hardened oils are blended with fully hydrogenated hardstock in varying proportions to produce a product which is approximately 85% oil and 15% solid at room temperature. The quality and texture of shortenings depend on incorporated gas, plasticity and consistency, and solid to liquid ratio. These physical characteristics are determined by the crystal phase of the fats used and the method of preparation.
In general, the method of attaining the beta prime crystal form desired for plastic shortenings is to use a suitable beta prime tending highly hydrogenated or saturated hardstock. Conventional beta prime tending hardstocks contain triglycerides that may undergo polymorphic transformations and crystal size changes on processing and storage and/or on temperature variations under stress conditions. This transformation results in a shortening which has a poor appearance, poor volume and poor performance. Further, the hydrogenation process causes transisomeric forms of the mono and polyunsaturates to form.
It has been suggested in the literature that the consumption of trans fatty acids and saturated fatty acids can increase the amount of LDL cholesterol in the body, and that consumption of trans fatty acids also can reduce HDL cholesterol levels. There have been various shortening compositions proposed in an attempt to reduce the trans fatty acids and saturated fatty acid content in shortenings. Exemplary compositions are described in US publication 2005/0271790, U.S. Pat. No. 5,106,644, U.S. Pat. No. 6,033,703, U.S. Pat. No. 5,470,598, U.S. Pat. No. 4,156,021 and U.S. Pat. No. 6,461,661. Among various shortening formulations available, VREAM® formulated using partially hydrogenated oil and a heavily hydrogenated oil contains the total amount of partially hydrogenated oil and a heavily hydrogenated oil is about 50%, VREAM®NH formulated without use of hydrogenation contains the total amount of trans plus saturated fatty acids is about 52%, and VREAM RighT® formed by using a hydrogenated base stock and a fully hydrogenated oil contains the total amount of trans plus saturated fatty acids is about 32%.
There is a continuing need for shortenings having reduced levels of saturated fats and trans fats, and acceptable physical properties for handling and food preparation.